The formation of tetrabromobenzoates has been disclosed by the prior art as being a minor, undesirable by-product in the synthesis of tetrabromophthalates from tetrabromophthalic anhydride. See, e.g., U.S. Pat. Nos. 5,049,697 and 5,208,366, both to Bohen et al; and Spatz et al., 8 Ind. Eng. Chem. Prod. Res. Develop., 391 (1969). In those references, tetrabromobenzoate is formed through decarboxylation of a reaction intermediate, and conditions are stated by which this undesirable side-reaction can be avoided.
The direct synthesis of tetrabromobenzoates has preferably been accomplished in the prior art through esterification of tetrabromobenzoic acid using an expensive metal or organometallic esterification catalyst. See, U.S. Pat. Nos. 5,049,697 and 5,208,366, both to Bohen et at. A disadvantage to this method is that tetrabromobenzoic acid is not readily available, and therefore must be synthesized prior to esterification. The esterification of tetrabromobenzoic acid requires long reaction times (22-70 hours), and requires the use of a metal or organometallic esterification catalyst which necessitates the complicated removal and disposal of the catalyst at the end of the reaction.
A need therefore exists for a simpler, faster and less expensive method of converting tetrabromophthalic anhydride to tetrabromobenzoate in high yield. The present invention addresses that need.